WASHINGTON (AP) — Defense Secretary Ash Carter intends to double the length of fully paid maternity leave for female service members and will also work to boost time off for paternity leave and adoptions, U.S. officials said.

Carter also intends to expand health care coverage to include more benefits for women trying to get pregnant. He also will direct the military services to expand the hours that military child care facilities are open and the number of children that can be accommodated, the officials said.

The proposals to be announced Thursday are part of Carter's ongoing effort to modernize the military and make it more competitive as it seeks to retain and recruit quality forces. He's already pushed past Marine Corps objections to allowing women to apply for combat jobs and has expressed a willingness to consider allowing transgender people serve openly.

The officials weren't authorized to discuss the plans publicly and spoke on condition of anonymity.

Officials said the military service chiefs and leaders largely endorsed the changes. There were concerns, however, expressed mainly by the Army and Marine Corps about the impact of any significant increase in maternity leave.

The maternity leave issue is complicated by the fact that Navy Secretary Ray Mabus already increased paid time-off for Navy and Marine Corps forces to 18 weeks. His decision last July tripled the current military leave of six weeks. The Marine Corps and Army, however, raised worries about extending leave to 18 weeks, saying it would keep key combat support troops off their jobs for too long and make it difficult to cover their posts by shifting personnel around.

Carter's decision to settle on 12 weeks would force the Navy to scale back its 18-week leave and make accommodations for those who may already have planned or started the longer time off.

The planned increase for paternity leave would go from 10 days to two full weeks. And officials said Carter wants to expand the current three-week leave for an adoptive parent, and allow the second parent to take two weeks off, if that person is also are in the military. The paternity and adoption leave changes would require approval from Congress.

The child care plan would increase the minimum time the facilities are open to 14 hours, from the current 12. Carter also wants the services to modernize and improve the child care system to reduce waiting lists and increase the number of children who can be served.

Carter was first asked about expanding maternity leave last September by a pregnant Army soldier, after the Navy had already announced it was going to increase maternity leave from six weeks to 18 weeks. At the time, Carter said he was waiting for the services to advise him on the subject. But he also told her "we are going to march in lockstep."

Under current law, the service secretaries have the authority to adjust the amount of time on leave.

The health care coverage is complex, but would likely involve increased benefits for women seeking more extensive fertility and pregnancy assistance. Specifically it would extend health care coverage to women seeking to freeze their eggs.

Pregnancy is a key issue for military women, who often have to deploy for months at a time and try to plan childbirth around their more stable duty assignments.

The expansion of family leave benefits is the second phase in a broader campaign by Carter to modernize the military and drag the often-antiquated Pentagon bureaucracy into the 21st century.

Last November he rolled out a series of initiatives aimed at attracting and retaining quality service members. They ranged from increasing internships to changing the retirement system to allow investments in a 401(k)-type retirement plan.

Many of the changes are an effort to align the Pentagon with the corporate world, strengthen ties with high-tech companies and bring the best from that field into the Defense Department.

"While the military cannot and should not replicate all aspects of the private sector, we can and should borrow best practices, technologies and personnel management techniques in commonsense ways that work for us so that in future generations, we'll keep attracting people of the same high caliber we have today," Carter said in November.